Tumor-derived cell lines have served as vital models to advance our understanding of oncogene function and therapeutic responses. Although substantial effort has been made to define the genomic constitution of cancer cell line panels, the transcriptome remains understudied. Here we describe RNA sequencing and single-nucleotide polymorphism (SNP) array analysis of 675 human cancer cell lines. We report comprehensive analyses of transcriptome features including gene expression, mutations, gene fusions and expression of non-human sequences. Of the 2,200 gene fusions catalogued, 1,435 consist of genes not previously found in fusions, providing many leads for further investigation. We combine multiple genome and transcriptome features in a pathway-based approach to enhance prediction of response to targeted therapeutics. Our results provide a valuable resource for studies that use cancer cell lines.
BACKGROUND-Duplications and deletions in the human genome can cause disease or predispose persons to disease. Advances in technologies to detect these changes allow for the routine identification of submicroscopic imbalances in large numbers of patients.
We report a recurrent microdeletion syndrome causing mental retardation, epilepsy and variable facial and digital dysmorphisms. We describe nine affected individuals, including six probands: two with de novo deletions, two who inherited the deletion from an affected parent and two with unknown inheritance. The proximal breakpoint of the largest deletion is contiguous with breakpoint 3 (BP3) of the Prader-Willi and Angelman syndrome region, extending 3.95 Mb distally to BP5. A smaller 1.5-Mb deletion has a proximal breakpoint within the larger deletion (BP4) and shares the same distal BP5. This recurrent 1.5-Mb deletion contains six genes, including a candidate gene for epilepsy (CHRNA7) that is probably responsible for the observed seizure phenotype. The BP4-BP5 region undergoes frequent inversion, suggesting a possible link between this inversion polymorphism and recurrent deletion. The frequency of these microdeletions in mental retardation cases is approximately 0.3% (6/2,082 tested), a prevalence comparable to that of Williams, Angelman and Prader-Willi syndromes.
Lung cancer is the leading cause of cancer-related mortality worldwide, with non-small-cell lung carcinomas in smokers being the predominant form of the disease. Although previous studies have identified important common somatic mutations in lung cancers, they have primarily focused on a limited set of genes and have thus provided a constrained view of the mutational spectrum. Recent cancer sequencing efforts have used next-generation sequencing technologies to provide a genome-wide view of mutations in leukaemia, breast cancer and cancer cell lines. Here we present the complete sequences of a primary lung tumour (60x coverage) and adjacent normal tissue (46x). Comparing the two genomes, we identify a wide variety of somatic variations, including >50,000 high-confidence single nucleotide variants. We validated 530 somatic single nucleotide variants in this tumour, including one in the KRAS proto-oncogene and 391 others in coding regions, as well as 43 large-scale structural variations. These constitute a large set of new somatic mutations and yield an estimated 17.7 per megabase genome-wide somatic mutation rate. Notably, we observe a distinct pattern of selection against mutations within expressed genes compared to non-expressed genes and in promoter regions up to 5 kilobases upstream of all protein-coding genes. Furthermore, we observe a higher rate of amino acid-changing mutations in kinase genes. We present a comprehensive view of somatic alterations in a single lung tumour, and provide the first evidence, to our knowledge, of distinct selective pressures present within the tumour environment.
Purpose Mutation in isocitrate dehydrogenase 1 (IDH1) at R132 (IDH1R132MUT) is frequent in low-grade diffuse gliomas and, within glioblastoma (GBM), has been proposed as a marker for GBMs that arise by transformation from lower-grade gliomas, regardless of clinical history. To determine how GBMs arising with IDH1R132MUT differ from other GBMs, we undertook a comprehensive comparison of patients presenting clinically with primary GBM as a function of IDH1R132 mutation status. Patients and Methods In all, 618 treatment-naive primary GBMs and 235 lower-grade diffuse gliomas were sequenced for IDH1R132 and analyzed for demographic, radiographic, anatomic, histologic, genomic, epigenetic, and transcriptional characteristics. Results Investigation revealed a constellation of features that distinguishes IDH1R132MUT GBMs from other GBMs (including frontal location and lesser extent of contrast enhancement and necrosis), relates them to lower-grade IDH1R132MUT gliomas, and supports the concept that IDH1R132MUT gliomas arise from a neural precursor population that is spatially and temporally restricted in the brain. The observed patterns of DNA sequence, methylation, and copy number alterations support a model of ordered molecular evolution of IDH1R132MUT GBM in which the appearance of mutant IDH1 protein is an initial event, followed by production of p53 mutant protein, and finally by copy number alterations of PTEN and EGFR. Conclusion Although histologically similar, GBMs arising with and without IDH1R132MUT appear to represent distinct disease entities that arise from separate cell types of origin as the result of largely nonoverlapping sets of molecular events. Optimal clinical management should account for the distinction between these GBM disease subtypes.
Angiogenesis plays a crucial role during tumorigenesis and much progress has been recently made in elucidating the role of VEGF and other growth factors in the regulation of angiogenesis. Recently, microRNAs (miRNAs) have been shown to modulate a variety of physiogical and pathological processes. We identified a set of differentially expressed miRNAs in microvascular endothelial cells co-cultured with tumour cells. Unexpectedly, most miRNAs were derived from tumour cells, packaged into microvesicles (MVs), and then directly delivered to endothelial cells. Among these miRNAs, we focused on miR-9 due to the strong morphological changes induced in cultured endothelial cells. We found that exogenous miR-9 effectively reduced SOCS5 levels, leading to activated JAK-STAT pathway. This signalling cascade promoted endothelial cell migration and tumour angiogenesis. Remarkably, administration of anti-miR-9 or JAK inhibitors suppressed MV-induced cell migration in vitro and decreased tumour burden in vivo. Collectively, these observations suggest that tumoursecreted miRNAs participate in intercellular communication and function as a novel pro-angiogenic mechanism.
Although angiogenesis inhibitors have provided substantial clinical benefit as cancer therapeutics, their use is limited by resistance to their therapeutic effects. While ample evidence indicates that such resistance can be influenced by the tumor microenvironment, the underlying mechanisms remain incompletely understood. Here, we have uncovered a paracrine signaling network between the adaptive and innate immune systems that is associated with resistance in multiple tumor models: lymphoma, lung and colon. Tumor-infiltrating T helper type 17 (T(H)17) cells and interleukin-17 (IL-17) induced the expression of granulocyte colony-stimulating factor (G-CSF) through nuclear factor κB (NF-κB) and extracellular-related kinase (ERK) signaling, leading to immature myeloid-cell mobilization and recruitment into the tumor microenvironment. The occurrence of T(H)17 cells and Bv8-positive granulocytes was also observed in clinical tumor specimens. Tumors resistant to treatment with antibodies to VEGF were rendered sensitive in IL-17 receptor (IL-17R)-knockout hosts deficient in T(H)17 effector function. Furthermore, pharmacological blockade of T(H)17 cell function sensitized resistant tumors to therapy with antibodies to VEGF. These findings indicate that IL-17 promotes tumor resistance to VEGF inhibition, suggesting that immunomodulatory strategies could improve the efficacy of anti-angiogenic therapy.
Hepatitis B virus (HBV) infection is a leading risk factor for hepatocellular carcinoma (HCC). HBV integration into the host genome has been reported, but its scale, impact and contribution to HCC development is not clear. Here, we sequenced the tumor and nontumor genomes (>803 coverage) and transcriptomes of four HCC patients and identified 255 HBV integration sites. Increased sequencing to 2403 coverage revealed a proportionally higher number of integration sites. Clonal expansion of HBV-integrated hepatocytes was found specifically in tumor samples. We observe a diverse collection of genomic perturbations near viral integration sites, including direct gene disruption, viral promoterdriven human transcription, viral-human transcript fusion, and DNA copy number alteration. Thus, we report the most comprehensive characterization of HBV integration in hepatocellular carcinoma patients. Such widespread random viral integration will likely increase carcinogenic opportunities in HBV-infected individuals.[Supplemental material is available for this article.] . HBV integration into the host genome has been reported both in tumors (Gozuacik et al. 2001;Murakami et al. 2005;Saigo et al. 2008) and in nontumor liver tissue from HBV-infected individuals (Mason et al. 2010), although such integration is not essential for HBV replication. The relative extent, mutation model, and the functional impact of HBV integration in host genomes is not clear due to the lack of an unbiased approach to identify and quantify genome-wide HBV integration sites. Recent advances in sequencing technologies (Meyerson et al. 2010) provide an opportunity to investigate the global extent, mutation model, and functional impact of viral integration in the host genome. Recently, a primary hepatitis C virus-infected HCC patient has been subjected to whole-genome sequencing, and many somatic mutations were reported (Totoki et al. 2011). However, as an RNA virus, HCV never integrates into the host genome during its life cycle; therefore, liver cancer with HCV infection is not an optimal model to study viral-human genomic interactions. To that end, sequencing the genome and transcriptome of an HBV-positive HCC patient provides a great opportunity to reveal the functional impact of viral integration on the host genome.
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